Zero
by trufflemores
Summary: 4.15. Based on the "Enter Flashtime" trailer. The newest meta detonates a bomb. There is no time left to stop it. Barry finds Iris.


"She, she detonated a bomb."

"Where?" Iris asks.

"Right here," Barry pants, staggering into the Cortex. "If you – _hahhh_ , if you stand still long enough, you can feel the heat. Feel it?"

Iris frowns. "It's detonating slowly," she hypothesizes.

Barry shakes his head. He's out of breath, but he can't slow down. Two deep breaths, and Central City is a crater. "No, no, it's happening in real time, we're just – we're in the Speed Force," he explains, gusty and terrified. "We're in a – pocket alley to the Speed Force. I've turned – a dimensional straw – into a tunnel. Except it's – a lot smaller than a straw."

Staggering over to the eraser board, there's-no-time-to-explain, he scoops up a marker in a shaking hand. Numbers jitter across the board as he writes. He needs to find a solution, to search for a more meaningful response to catastrophe than _math_ , but math is safe, science is _safe_ , and the only thing real to him is the glacially melting markerboard under his hands.

"Stay with me. Imagine … a garden hose," he says, sketching out a shaky snake across the board. "We know it has … thr-three dimensions, ordinarily. A fourth in time," he adds, waving a hand dismissively. He drops the marker. Bending to pick it up, he jabs the markerboard and explains, "But if you're looking at a three-dimensional garden hose from a high-enough vantage point – let's say an airplane."

He has to pause to draw in a deep, wheezing breath. He can't do this, he is going to die, he _can't do this_. With a shuddering inhale, he resumes. "If you-look-at-the-hose-from-the-air-it's like a _line_ , a flat surface with only _one-_ dimension," he gasps. "But we kn-kn-know that it's still a three-dimensional hose. It just _looks_ flat. Still with me?"

Iris holds his left elbow, stabilizing him when he tips vertiginously on his feet. "Barry, honey, you're going to pass out."

Shaking his head violently, he says, "Flat line – full-sized hose. We see a flat line from the air because we're – too far away, it's too sm-small." Breathing through his mouth, he pauses for a miniscule, hyperventilating breath. All the confining pressure, the desperate lurch of real-time competing with Speed-time, makes it feel like he's not only drowning in quicksand, but also being hauled out into the vacuum of space. He can barely blink to refocus. Sweat drips down his forehead.

"When we zoom in on it, _then_ we s-s-see the hose again." He drags the marker across the board, but it splatters unexpectedly, a starburst of blue ink. He jumps backward and trips over his own feet, landing hard on his side. Iris moves to help him, but like a bad computer virus, he's already jittering back to his feet, one-two, one-two, one-two-three- _up_. She puts a stabilizing arm around his waist. He's sweating profusely and still it's only getting faster-faster-hotter- _run_.

"I'm okay," he lies. "'m okay." He gazes at the board with glassy eyes. "Rolled-up objects look flat from a great enough distance," he says, focusing on every word. He can't pry his brain away from the topic; his mind is overloading, and math is his only escape. He will cave and take a breath if he allows himself to divert course. He plows on.

"So imagine – a universe full of lines, that are actually hoses. Or straws. We think each line is – is – one-one- _one_ dimensional, from our viewpoint. But each li-li-line is actually a _three_ -dimensional object." He snags a different red marker from the stack, flooding the board with lines, arching around each other. "Our universe is fu-full of lines. Some straight, some wavy. We c-c-ca-can't see past a certain r-re-resolution, so we're stu-stu-st-stuckkk in an airplane looking down at a line that m-m-m-might be a garden hose."

He drops the marker. This time, he doesn't retrieve it. The board is a stucco illustration depicting a madman's last breath. Iris gazes at it in wonder, her arm anchored around his waist. He would fall without it. "If we-we-we could somehow magnify – the view, we would—"

Retching, he bends in half, but nothing comes up. He's just gagging for breath, like a sprinter after a hard run. "Hoses," he grunts, hands on his knees. "Lots and lots'a hoses." His words trip over each other in the radiant air. "We'r'in'a hose," he slurs. "A really, really small hose." His knees hit the floor. His heart is pounding, even for him.

"S'what Cisco taps into," he adds deliriously. Iris kneels beside him, arm around his shoulders. His suit is glued to his back, burning into his skin. Thankfully, the outer layer is cool; she doesn't reel backwards in alarm at the heat. She seems almost as thunderstruck as he feels. "He sees things from a _string_ viewpoint," Barry explains. "Way, way, way smaller 'n atoms. Smalls enough to see all these lines as – hoses.

"Strings are – strings are smaller 'n hoses, so instead'a lookin' down at 'em from an airplane, he's … he's in _side_ the hose. Popping in and outta nowhere, it seems, using these tunnels to get ar-around." He tries to get back to his feet, but there is a mountain on his shoulders. He stays down, instead. He shakes hard. Iris doesn't move. "Do you understand?" he asks, voice thin.

Slowly, she surmises, "We're in a quantum tunnel."

A little laugh escapes him. He's so grateful for it. What a beautiful way to die: with laughter on his last breath. "That's – a really good description, actually, but it was taken," he huffs, out of breath but still desperate to be heard. "Physicists call it a – a _rolled-up dimension_. Cisco – Cisco 's here because he can Vibe. This is his lane, his … quantum universe. We're here for the same reason."

"Speed Force."

He nods, gaze on the tile floor. It's melting slowly, too. Everything is melting. They're already out of time. "Speed Force," he echoes. "'m able to – to tap into the Speed Force directly, but it means I have to – I have to keep moving at super-atomic speeds to maintain the tunnel instead of the line. It's – _hnnn_." He grips his chest as a lurch of pain ruptures in his heart. Somehow, it keeps beating. He goes on. "It's really-really-really hard," he pants. "I don't – I don't think I can keep it up much longer."

"So how do we stop this?" she asks, to the point.

He shakes his head. A tear drips down his cheek. "I love you," he warbles, straining to keep the emotion out of his voice long enough to speak. "I love you more than anything, Iris, but I – I'm at my limit. As soon as I slow down, the dimension will collapse back down to its normal size and we won't be protected from the blast. You can feel the heat?" he adds, because it's pouring from him. She nods slowly. "It wants in, it wants to speed up, it – it _wants_ ," he rasps.

"If I slow down, we'll die," he says bluntly. " _I_ can escape into the Speed Force, but that doesn't help you, or Cisco, or Joe, or anybody. Everyone, _everyone_ in Central City will die. Everyone in a three-hundred-mile radius will be doused in a lethal wave of radiation traveling faster than the speed of sound. Two-and-a-half million people are in the direct crossfire of this bomb. And at this speed…."

He struggles upright, taking her hand and squeezing it gently. "This is how fast I am at this speed," he says, voice barely a whisper. "It would take a hundred thousand years at this pace to evacuate that many people, and that wouldn't even take care of the fallout. We're less than a trillionth of a second away from one of the greatest catastrophes humanity has ever known. Nuclear winter is coming and m-m-m-millions of people are going to die."

She squeezes his hand, expression mirroring his aghast horror. "Bar," she says softly. At a loss for words, she reaches up to cup his face in both hands, stroking her thumbs over his overheating cheekbones. According to the suit's readings, he's approaching 168 degrees Fahrenheit inside the suit. Whatever his internal temperature is, his organs are creeping towards the boiling point. "Can we diffuse the explosion?" she asks.

He loves her for the 'we' because he knows that he can't do this alone. But, equally devastatingly, he knows that they can't do it together. "N-no. It's not about shrapnel," he explains, tongue heavy in his mouth. His lungs hurt; his chest heaves like a racehorse's. "This is one of those times wh-wh-where it _is_ the wind that will kill you, and not just what it c-carries. The blast itself is lethal. I can catch bullets, but I-I-I can't stop a nuclear wave."

Another tear hits the ground and fizzes. Iris leans up and kisses his forehead, holding him steady even as he falls apart, threatening to take his entire world with it. "Iris," he pleads. "I can't – I can't run. I can't. Because I know what will if I do – you'll all die." He sobs, a wet, suffocating sound, like blood in his lungs. It's just an illusion – but it is so _heavy_. He has to get out of here; it's killing him.

He is the source of the tremendous energy required to keep the tunnel upright. Iris is merely along for the ride. He's so grateful. It would kill him to see her in this much pain. "If I take you with me," he carries on, voice dissolving into stutters once more as he finishes, "th-th-then I'm c-condemning _everyone_ else to di-di-di-die. I can't save anyone else – there's no time." There's-no-time. His suit is still getting hotter. He'll past out in a few more million, billion, billion, billionths of a second. Just thinking about it makes the edges of his vision go grey. "I can go back in time," he adds, desperate, bearing the weight of the universe, "but then y-you'll die, and so will everyone else in the blast radius."

He sobs, and she brings his head to her chest, cradling him to her for one of those million, billion, billion, billionths of a second. A soul-deep anguish relents, even though the heat and pain do not. He shakes. He can feel her ring on the back of his neck, one hand tangled in the sweat-soaked hair.

The profundity of his original declaration strikes him: he didn't marry an Iris; he married _her_. It doesn't matter that there are an infinite number of Irises out there, that he can always find one, past, present, or future. In spite of his own infinite number of doppelgangers, his own life, as is, _matters_. So does hers. It is a principle he holds tight to his chest, a principle that haunts him when he falls asleep, imagining how little the universe at large would care if one more Barry Allen died.

He – in his centrality, his originality, his fundamental individuality – is irreplaceable. And so is she. To lose her would be a loss beyond comparison. It is the fabric of his universe: no matter how many others exist, there is only ever _one_ , one version of that person he loves. He can love the others. Indeed, many are so indistinguishably similar he wouldn't be able to tell the difference. But they won't ever be _her_.

And she will die if he leaves her to this fate. They all will. And so will two-point-five million people, minimum.

"Tell me what to do," he begs. "I – I don't know what to do. I can't—" He inhales, and there's a crackling sound in his chest. Pain lances across his ribs. Like dainty little wishbones, ribs snap under the extraordinary pressure. He barely notices: the suit's temperature is assailing all of his senses, now, beginning to haze his vision, too. The coolant systems are online, but his speed is so spectacular that they're only able to keep him from catching on fire. "I don't know what to do," he gasps, trembling in her arms. "Please tell me."

She scratches the base of his skull lightly, the way he likes it. There's a serenity to her that bleeds into him, even though he cannot escape the vice of his own reality coming apart at the seams. Anything to protect her, to protect them, to protect _this_ – the very last second of their lives – just one million, billion, billionth of a second longer.

It's absurd how one million, billion, billionth of a second is already one thousand times longer than the preceding decillionth of a second. He can't fathom it, can't explain how one thousand instants can simply _disappear_. The Big Bang was like this, he muses, hugging her around the waist. It happened in an instant, an infinitesimally brief instant, a slice of time so small that it truly confounds the human mind's ability to understand it.

To slow down the Big Bang to the stately pace of one Speed-time second for every decillionth of a real-time second, it would take more Speed-time than has passed since the beginning of the multiverse – or will ever pass, unto the very end – to observe the birth of the cosmos. The tape of that first momentous occasion would still be rolling well after the ten thousandth universe had come and gone. It would take a billion, billion universes to watch that one second of real-time become everything that ever was.

That is where he rests, now, hugging the pocket dimension between multiverse and Speed Force, an alley of untold profundity separating the universes. It is too small for scientists of his time to study it. It may take many more generations to begin to understand this strange place, to transform ordinary people into the extraordinary by observing this tiny, inexplicably strange place.

He won't be there for it. Indeed, once the sand sifts through his fingers now, he won't be there for anything else.

If he can keep up this speed – an impossible task, a Sisyphean task – then he can enjoy those billion, billion lifetimes of the universe encapsulated in this single spectacularly wrong instant. It won't last. It can't last. But it is an extraordinary thought, that he could live out his own life trillions of times over, here, with Iris.

He could save _everyone_. He could end world hunger, end all warfare, end all disease. He could stop every crime and nurture every blade of grass, resurrect every dinosaur and write every book, do everything conceivable a thousand times over, and still have a nearly infinite amount of time left over. He could invent technologies so advanced they seemed magical, and still find more magical technologies. He could wander to the ends of the observable universe, and still have time to double back and inspect every grain of sand.

It is an absurd amount of time, all the time in the cosmos, a billion, billion times over.

But he can barely upkeep this standstill pace for even a few moments. His tenuous hold is slipping. He can feel everything collapsing, threatening to fall apart any moment. When it happens, it will appear instantaneous. That little rolled-up dimension will become a line once more; their little world will implode. Hundreds of millions of people will die, but they won't be there to see it.

Everything is about to begin, and end.

Sitting back on sore haunches, breathless and still full of love for her, Barry regards Iris. He wants to say something, but there are no words left to him. Resting his forehead against hers for a moment, he holds it for a few of those fractions of a second. Time races by even faster now. There is no more time to count the sand, one-by-one.

He rises, slowly, to his feet. She follows him. He says softly, "I know what to do."

She warns, "Barry." His tone gives him away. There's fear in her eyes.

He squeezes her elbows gently before letting go. Hurting like a broken doll, he feels strangely purposeful, reassured. "I'm going to find it," he insists, because he knows – he knows what to do.

She says, "Don't."

He insists softly, "I love you."

She surges up to kiss him, and a sob of breath escapes her. "Barry." When he pulls away, she finally says it back: "I love you." And it gives him the courage to let go.

He has to look away from her, then, back to her as he treads the final steps towards that radioactive heart. The hallway around the Cortex is already molten. The cube is five hundred meters away. Already, it's beginning to warp the building.

Cisco found it – and it was Cisco and he who determined that it could not be dismantled – but Cisco has since abandoned the exploding cube to search for a solution, per orders. He won't be back in time to stop it – not now, not with their fragile pocket universe threatening to collapse, for the immortal realm to lunge back into the mortal one.

His feet burn on the ground, even with the boots. He keeps going.

He cannot disarm the exploding bomb. They can't diffuse it. And there's no time to escape it.

Steeling himself, he lurches towards the centerfold of creation and destruction. The singularity. The original was far smaller, and grander, and ultimately the greatest thing that ever happened. This is simply the worst that will ever happen to him and his own.

The events are equivalent, in his experiences. For all intents and purposes, they are nearly the same.

He builds up from his death-march into a loping jog. The Speed Force blurs the metal walls together. He slides the suit's protective visor in place, and it shields his eyes as the light becomes brighter and brighter and brighter. Eventually, even it is insufficient to cool the blinding blast of white fanning outward. Still he pushes onward, moving faster. His pace picks up; his gait switches from canter to gallop.

And then, at last, one hundred meters from the epicenter, he feels the wall of lava-like heat, and bursts into a run.

He moves so quickly his own eyes cannot keep up; one moment, he is safely outside the immediate blast, and the next, he is plunging into a Hadean inferno, searing every inch of exposed skin, boiling his eyes and saliva. He doesn't consciously continue – he could not – but somehow his step increases. Any outsider would see only an orange lightning beast in the shape of a human surging on, until even the shape deteriorated, and there was only a bolt of blue light in its place.

It is that blast that arcs towards the blast, slowing time down, down, down, until slowly, the blue light halts, and the room darkens as the light recedes from the edges inward.

The singularity reverses as the Speed Force breaches the photonic speed of light. Time reverses, revisiting where the blinding bright white was mere moments before. Moments. Such a long time, for absolutely nothing, and everything, to happen.

The instant the blue bolt reaches the cube, the singularity collapses.

Then the bolt from the blue vanishes with the cube, and Central City takes a real-time breath, and does not die.

. o .

Into the Speed Force's hands, Barry delivers the killing power of the bomb.

Divorced from its context, the blast is simply heat, and filling the ember-red eyes of the Black Flash watching him. Barry sees his own visage under the mask, but it's an aged, changed version of himself. All of the biological needs so consuming on Earth fade to background noise here; there is no need to breathe, no human heart to beat. He is only what the Speed Force imagines him to be.

Slowly, the Black Flash reaches out, curls Its hands around the desolate cube, and crushes it between its fingers. Barry waits for a blast, but it never comes. Indeed, the Black Flash merely opens Its hand and looks at him expectantly. _I have seen the beginning and end of your universe_ , It muses aloud. Its mouth does not move, but Barry still hears it. _I have seen the beginning and end of every universe._

 _Yet I am still here._ It takes a seat on a rocking chair. A familiar porch – their childhood porch – materializes around them. A chair opposing appears, and Barry takes a seat. An entire world melts into view – a memory like a reality – and thunder rumbles in the distance. The Black Flash rocks in Its chair, staring unblinkingly out at the horizon. Its expression is utterly implacable.

Slowly, Barry rocks in his own chair, matching the Black Flash's pace. It is strangely serene, the familiar sound of wood crackling gently. The air smells heavy with rain. The house behind them is warm with open windows, letting summer in, and the sound of someone baking a cake. He is suddenly sure that it is his seventeenth birthday.

Even though the Black Flash is seated and utterly nonplussed outwardly, Barry senses great anticipation, even _joy_.

They love this memory, he knows, and isn't surprised when Joe finally opens the door and steps outside. A chair appears next to the Black Flash, and Joe takes it. Barry feels peace wash over him. Everything about the scene – the familiar street, the familiar _day_ , March 14, 2006 – gives him a sense of completion. Of _home-coming_.

"We've lived your life so much, it's almost been our own," the Speed Force says, through Joe. The Black Flash turns to regard him, hanging onto every word. Despite its looming stature and sharp-edged demeanor, it seems suddenly child-like, full of respect for the man next to It. "It's been a good life," the Speed Force adds. Looking at the Black Flash, he smiles. "You've gotta wait. Iris is still out fetching candles."

Barry watches the two of them, tempted, suddenly, to go find Iris, just as he did on that day. She wasn't expecting him, so she shrieked when he hugged her from behind before laughing and smacking his arm. He was an angsty teenager, a moody teenager who fought with Joe and dated Becky Cooper, who made him feel like the monster his dad wasn't, but he still regards the entirety of his childhood with general magnanimity.

He likes to revisit these moments. Indeed, he's back here in his dreams, and still it is not as real as this.

The Black Flash looks over at Barry and meets his eyes. Barry doesn't see his older doppelganger, hardened and refined by the Speed Force, but the lanky seventeen-year-old looking back at him, the cowl almost humorous on his soft face, his babyface. There's still an almost wolfish glean to those eyes, ready to push boundaries and have fun, eager to delve into that _delicious_ cake baking indoors. Then the Black Flash looks back at Joe, and It is old and worn again.

At last, Joe turns to regard him. Another rumble of thunder invites them to go inside, or stay tuned: more is coming. "We never wanted you to suffer," the Speed Force, through Joe, says. "We only wanted you to live. Freely. Deeply. Meaningfully. Sometimes that meant suffering. Sometimes that meant basking. We could, perhaps, have tilted the board more in your favor, and at times, we certainly did."

The Black Flash looks at him. Barry feels small under their gazes. The Black Flash's glides back to the horizon, thoughtful. It stops rocking. Joe picks up the rhythm instead in his own chair.

"We can do this forever," Joe adds, and something – thrilling, and sad, and fearful fills Barry's chest at the thought. "Our connection to existence supersedes all but the end-that-is-not-coming. So. We can send you home again." He pulls a pack of gum out of his pocket, and fishes out a stick for the Black Flash. It looks at him, then takes the stick, unwrapping it carefully in black clawed hands.

"We can give you a nice new body to make up for the one we stole when you outpaced your own self and became nothing, but us." The Black Flash chews on the gum. Barry wants to ask for a stick, but he doesn't need to: Joe holds one out to him, and he takes it. "We can do things that appear to be magical, because of their scope," the Speed Force continues, replacing the gum package in his pocket. Barry bites into his own stick, and has to close his eyes for a moment at how _good_ it tastes. Everything is better in memory. "So. If you wish to go home, then say the word, Barry."

Chewing on the gum, Barry looks out at the horizon, inadvertently mirroring the Black Flash when they both blow a bubble. He actually laughs; the Black Flash merely chews Its piece without remark. "Or stay," Joe offers, and Barry looks at him, something – tight, and longing, and hopeful in his chest. "Be free of the suffering so pervasive to your world, and join us in ours. We still do what we can for your world," he adds with a nod," and there are others who can step into your role and protect the city. It is not about what the world needs, Barry. It is about what you _want_. Do you want to return?"

Barry thinks about Iris coming home with birthday candles, and the sweet taste of the cake, and the infinite joys to be found here from countless other Barrys' lifetimes. He has lived a full life, a fulfilling life, in just his twenty-nine years. He could rest here and know that he had done more than most people ever would. When the Speed Force invited him to end his race and spend time with it, he'd feared that it would be torture. On the contrary: returning was the hardest part.

The Speed Force is a beautiful, time- _full_ place. And there is no suffering here.

But it's not home. And just as owning every second of a trillion, trillion universes would not truly satisfy him the way that a real-time life would, so too would spending eternity in this surreal space not satisfy him. Not yet. _Someday,_ he thinks.

Aloud, all he says is, "I'll come home one day. For now - take me back."

. o .

Barry opens his eyes.

He's lying on the floor in the room with the cube, but there is no cube, and the concrete is cool underneath him. Indeed, the suit is brilliantly comfortable, _memory-of-a-thing_ comfortable. His heart beats steadily and comfortably. His ribs swell easily and immediately with a deep breath. The lack of pain – not merely the anticipated agonies of the bomb, but _all_ the aches, that deep, gut-twisting ache in his lower back from Zoom or that still tight pain in his left calf from Killer Frost – they're _gone_.

Breathing for a few moments in real-time, he closes his eyes again, marveling. He feels strong – ready. Healed. _Whole_.

Perhaps being reborn was the answer, he muses, as he hears voices approaching, ears thrillingly sharp to sound that should be at best foggy to shattered eardrums. At last, Cisco skids into the room, Iris at his heels. "Barry!" he squawks, and Barry opens his eyes, a little laugh bubbling out of him. Sitting up slowly, he feels a pleasant exhaustion, sleepy but not fatigued, _let's take a nap for a while_ tugging on his eyelids.

They almost crash beside him, and he wraps an arm around them both, chuckling helplessly because it is so _good_ to be _alive_.

"Hi," he greets them, holding on tight but not trembling. "I'm here. I'm okay."

It seems soft, surreal, important to say. Iris kisses his cheek; Cisco lets go slowly, reluctantly. The air between them is full of warmth and relief and palpable _almost_ destruction. "Hi," he tells Iris, and his smoke-clear voice is familiarly strong. He gets up on his knees so he can hug her better. "It's all right. It's gone."

"How did you—?" Cisco trails off.

Barry shakes his head a little, rubbing Iris' back slowly. "Blame the Speed Force," he says simply, and wonders how he got so lucky to experience the lightning under his veins, and the friendship of the Speed Force.

Knowing that even after the stars have burned out, he will sit alongside it and bask, is comforting. And knowing that the Speed Force is _happy_ , of all things, living this life of anguish and stress and profound, untainted joy –

It makes him happy, too.


End file.
